A Newly Designed Composite Gel Polymer Electrolyte Based on Poly(Vinylidene Fluoride‐Hexafluoropropylene) (PVDF‐HFP) for Enhanced Solid‐State Lithium‐Sulfur Batteries

446

270

All-solid-state lithium metal battery is the most promising next-generation energy storage device. However, the low ionic conductivity of solid electrolytes and high interfacial impedance with electrode are the main factors to limit the development of all-solid-state batteries. In this work, a low resistance-integrated all-solid-state battery is designed with excellent electrochemical performance that applies the polyethylene oxide (PEO) with lithium bis(trifluoromethylsulphonyl)imide as both binder of cathode and matrix of composite electrolyte embedded with Li 7 La 3 Zr 2 O 12 (LLZO) nanowires (PLLN). The PEO in cathode and PLLN are fused at high temperature to form an integrated all-solid-state battery structure, which effectively strengthens the interface compatibility and stability between cathode and PLLN to guarantee high efficient ion transportation during long cycling. The LLZO nanowires uniformly distributed in PLLN can increase the ionic conductivity and mechanical strength of composite electrolyte efficiently, which induces the uniform deposition of lithium metal, thereby suppressing the lithium dendrite growth. The Li symmetric cells using PLLN can stably cycle for 1000 h without short circuit at 60 °C. The integrated LiFePO 4 /PLLN/Li batteries show excellent cycling stability at both 60 and 45 °C. The study proposed a novel and robust battery structure with outstanding electrochemical properties.

Section: Resultsmentioning

confidence: 99%

Low Resistance–Integrated All‐Solid‐State Battery Achieved by Li₇La₃Zr₂O₁₂ Nanowire Upgrading Polyethylene Oxide (PEO) Composite Electrolyte and PEO Cathode Binder

Wan

Lei

Yang

et al. 2018

446

270

“…The solid‐state Li–S battery with the composite electrolyte shows a high initial capacity of 1478 mA h g −1 at 0.1 C and excellent cycling performance (remains 668 mA h g −1 after 1200 cycles at 1 C in Figure b and 1315 mA h g −1 after 50 cycles at 0.1 C). Tu and co‐workers prepared PVDF‐HFP/LAGP composite electrolyte by adding the nanometer fast ionic conductors fillers to the gel electrolyte, resulting in improved electrochemical performance (shows high initial capacity of 889 mA h g −1 at 0.05 C and better cycling performance than the liquid batteries). Wen and co‐workers used fast ion conductor (LAGP) and PEO‐based gel electrolyte to design a new multilayered structure, where LAGP can transmit Li‐ions quickly and absorb LiPSs (Figure c).…”

Section: Solid‐state Electrolytes For Preventing the Lipss Shuttlementioning

confidence: 99%

Progress and Perspective of Solid‐State Lithium–Sulfur Batteries

Lei

Shi

et al. 2018

212

154

Due to high energy density, low cost, and nontoxicity, lithium-sulfur (Li-S) batteries are considered as the most promising candidate to satisfy the requirement from the accelerated development of electric vehicles. However, Li-S batteries are subjected to lithium polysulfides (LiPSs) shuttling due to their high dissolution in liquid electrolyte, resulting in low columbic efficiency and poor cycling performance. Moreover, the Li metal as an indispensable anode of Li-S batteries shows serious safety issues derived from the lithium dendrite formation. The replacement of liquid electrolytes with solid-state electrolytes (SSEs) has been recognized as a fundamental approach to effectively address above problems. In this review, the progress on applying various classes of SSEs including gel, solid-state polymer, ceramic, and composite electrolytes to solve the issues of Li-S batteries is summarized. The specific capacity of Li-S batteries is effectively improved due to the suppression of LiPSs shuttling by SSEs, while the rate and cycling performance remain relatively poor owing to the limited ionic conductivity and high interfacial resistance. Designing smart electrode/electrolyte integrated architectures, enabling the high ionic transportation pathway and compatible electrode/electrolyte interface, may be an effective way to achieve high performance solid-state Li-S batteries. and strategies have been attempted to address the above main issues of Li-S batteries, including using sulfur host materials, [4] unique separators [5] and interlayer, [6] composite of electrolyte, [7] novel binders, [8] etc. However, these approaches can only solve problems to a certain extent. Some review papers have concluded and commented on above potential solutions. [9] Recently, solid-state electrolytes (SSEs) including gel, solid-state polymer, ceramic, and composite electrolytes are attracting increasing interest for application in Li-S batteries to fundamentally solve the issues of Li-S batteries caused by liquid electrolyte. Furthermore, nonflammable solid electrolytes would improve the safety performance of Li-S batteries remarkably. In the past few years, more and more research work focused on applying SSEs in Li-S batteries to solve the LiPSs dissolution. [10] Some review papers about Li-S batteries have also emphasized the significance of SSEs. However, until now, there are few review papers specially summarizing the progress and prospect of the solid-state Li-S batteries.This review aims to provide an overview of SSEs for addressing the major drawbacks of Li-S batteries, including the electrochemical reaction process of S cathode and its corresponding problems as well as traditional solutions, the recent research progress of solid-state Li-S batteries using gel, solidstate polymer, ceramic, and composite electrolytes, and strategies for overcoming the deficiencies of solid-state electrolytes such as low room-temperature ionic conductivity and high Solid-State Electrolytes interfacial resistance. In addtition, the mechanism a...

“…Moreover, the use of active fillers in GPEs can improve ionic conductivity . Li 1.5 Al 0.5 Ti 1.5 (PO 4 ) 3 (LATP) nanoparticles were into the PVDF‐HFP matrix can improve the lithium‐ion transference number and electrochemical stability …”

Section: Hybrid Electrolyte Systemsmentioning

confidence: 99%

Development and Challenges of Functional Electrolytes for High‐Performance Lithium–Sulfur Batteries

Wang

Chen

et al. 2018

151

110

Lithium-sulfur (Li-S) batteries, as one of the most important candidates of next-generation batteries, are famous for high energy density, low cost, and environmental friendly benignity. However, issues originating from polysulfide shuttle of common liquid electrolytes (e.g., capacity fade, poor cycle life, and safe issue) have hindered the applications of Li-S batteries in various occasions. This review summarizes the main efforts in the electrolytes of Li-S batteries, including liquid, solid state, and hybrid electrolyte systems. The development of functional electrolytes for Li-S batteries is hopeful to alleviate the problems Li-S batteries faced today. The liquid electrolytes circumvent the polysulfide shuttle and the resultant problems by utilizing different functional solvents, lithium salts, and additives. Solid-state electrolytes as promising electrolytes are optimized to enhance the ionic conductivity at room temperature and decrease the interfacial resistance. Hybrid electrolytes that consist of two or more single electrolytes may be considered as unique categories because they have the potential advantages than the single electrolyte systems. Challenges and perspectives of Li-S electrolytes are also proposed based on the requirement for high-performance Li-S batteries.be reduced to short-chain ones, which subsequently migrate back to cathode and are reoxidized to long-chain lithium polysulfide intermediates. This endless movement and shuttle of polysulfides between cathode and anode is generally called as polysulfide shuttle. During cycling, the shuttle effect of polysulfides continuously occurs and results in lower Coulombic efficiency and anode corrosion. [3a,4,5] c) Safety issues: the electrolyte solvents may be not stable when the high reactivity of lithium metal and the soluble polysulfides are present, which results in the gradual depletion of solvents and the gas expansion of batteries. [6] High flammable organic solvents increase safety hazard, when used under high-temperature conditions. [7] Moreover, the growth of lithium dendrites can potentially penetrate the separator, which leads to internal short circuits of batteries and serious safety issues. [8] In order to overcome the issues mentioned above and improve battery performance, some strategies have been examined, including the design of sulfur cathodes, [4,9] the protection of lithium anode, [10] and the optimization of electrolytes. [11] The electrolyte between cathode and anode is a crucial component as it affects the lithium-ion transport during the cycling process, which in part determines the batteries performance. [12] Electrolyte development is time consuming because it requires high-throughput experiment but is indispensable. Some works have therefore focused on the development of functional electrolyte in the last several years. Different roads lead to the same thing that usable electrolytes should possess many characters, such as high ionic transport, low viscosity, good chemical and electrochemical stability, nonflammab...